Leaked documents show the UK is pushing for watered-down EU air pollution laws to be weakened further, arguing they would cause pit closures leading to substantial job losses and the need to import coal.

The EU rules could help curb toxic nitrogen oxides (NOx) and sulphur dioxide (SO2) emissions, although campaigners criticised them following revelations that they were partly drafted by the same companies they were meant to regulate.

But a confidential government submission to Brussels, seen by the Guardian, says that the UK would have to import coal from Russia, Colombia and South Africa to meet the new standards, because British coal has such a high sulphur content.

This “would therefore lead to the loss of the principal market for UK coal and the closure of the UK’s coal mines,” the paper says. “The mine closures would also lead to substantial job losses – directly and indirectly within the supply chain – in areas of the UK with significant levels of unemployment and socio-economic deprivation.”

Greenpeace argued that because two-thirds of fossil fuel reserves must be left underground to avoid climate breakdown, the government should offer retraining and financial support to miners, instead of a lifeline to their bosses.

“To protect the profits of a few coal-burning energy firms the ‘greenest government ever’ is lobbying to water down air pollution rules that could save hundreds of lives and millions in NHS costs,” said Greenpeace’s head of energy, Daisy Sands. “Not content with locking consumers into higher bills by undermining the cheapest clean energy sources and home efficiency, ministers are now putting their health at risk by letting big polluters off the hook.”

The new EU rules are expected to be agreed early next year, before coming into force in 2020.

In April, the supreme court gave the government until the end of the year to present a plan for cleaning up the country’s polluted air, which is responsible for 29,000 early deaths every year. The government is expected to announce its plan for bringing the UK into line with the EU’s existing air quality directive next month.

The UK has been in breach of the EU’s nitrogen dioxide (NO2) pollution limits since 2010 and will not meet them until 2030 on current trends, according to government figures, raising the spectre of fines of up to £300m (€420) a year.

Alan Andrews, a lawyer for ClientEarth, which brought the supreme court case against the government, expressed dismay at the pro-coal stance in the leaked papers.

“It suggests that they are not taking the supreme court decision seriously and are not making a genuine attempt to achieve the emissions reductions as soon as possible,” he told the Guardian. “We would seriously consider further legal action if that is the case, after we have analysed the new plan.”